afternoon, the medical examiner's office identified the woman as 48-year- old san francisco resident diane sullivan. police say two nurses who were in the crowd heading to the park jumped in to help sullivan. the cement truck driver stopped across the street when he realized there was a problem, and hours later, he was in a police vehicle, obviously distraught. >> did you have a big cement truck with a big wheel base, and preliminary reports is she was curbside on her bike, riding, and somehow became entangled. >> reporter: the incident left many in shock. >> i never seen somebody try to get someone else breathing again actually in person. so that was unfortunate. i feel terrible. >> reporter: police are still trying to determine what caused the accident, but they say the cement truck driver is cooperating with investigators. live in san francisco, john sasaki, ktvu channel 2news. >>> a fatal interstate on 880 shut down westbound lanes through richmond for several hours this afternoon. the highway patrol says the accident involved several cars near the carlson boulevard exit around 1:15 p.